Reply to Coutrot et al.: Is Nitric Oxide Nephro- or Cardioprotective?

Abstract

the development of acute kidney injury. An association between high venous pressure (i.e., right atrial pressure or central venous pressure) and worsening renal function has been described in many different clinical settings, including patients who have undergone cardiac surgery and patients with heart failure (5). We suggest that the observed protective effect on kidney function in this study might be due to a decreased right ventricular afterload, which would decrease the right filling pressure and prevent renal venous congestion after NO inhalation (6). The population investigated in this study furthermore suggests this. Cardiopulmonary bypass was prolonged and most of the surgical procedures were for rheumatic valvular disease, including tricuspid valve surgery. These patients, approximately half of whom had pulmonary artery hypertension, had a high risk of postoperative right cardiac failure. However, data regarding the postoperative hemodynamic parameters are not presented. Unfortunately, the authors point out that transesophageal echocardiography or pulmonary artery catheterization is not the standard of care during surgery in their center—but postoperative monitoring of cardiac function, including the cardiac index and filling pressures (such as the central venous pressure), certainly is. Insights into the impact of inhaled NO on hemodynamics and right filling pressure would help us to better understand the potential mechanisms of nephroprotection and identify the patients who would most benefit from this therapy. n